Mars Rover Communications and Autonomy - Department of ...

rucksackbulgeAI and Robotics

Dec 1, 2013 (3 years and 7 months ago)

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Mars Rover

communications

and autonomy

Dr Anthony J H Simons (from NASA materials)

2

Rover and Lander


Different Configurations


Solo rover, or working with lander and/or orbiter?


Landing: arrest via rocket, parachute, or airbag?


Swarms: copters, biomorphs, penetrators


Different Control Strategies


Signals direct to rover, or via orbiter, lander?


Base, orbiter, lander, rover distribution of control


Sensors: pressure, altimeter, laser, radar, vision


Control: experiment deployment, data uplink


3

Example Missions


NASA Pathfinder Sojourner


July
-
September 1997


Lander base station plus small rover


http://www.jpl.nasa.gov/news/fact_sheets/mpf.pdf


NASA Mars Exploration Rovers


January
-
April 2004 (but still active)


Two independent rovers
Spirit

and
Opportunity

landed at
different locations


http://www.jpl.nasa.gov/news/fact_sheets/mars03rovers.pdf

4

NASA Pathfinder Sojourner

Image © Neil English, Exploring Mars, Pole Star Publications Ltd.

Antenna

Solar cells

Multi
-
wheel
drive

Steerable
front pair

5

Pathfinder Sojourner Lander

Airbags to
cushion
landing

Exit track
for rover

Lander
bounces
(like ball)

Airbags
deflate and
shell opens

Lander has
uplink

Image © Neil English, Exploring Mars, Pole Star Publications Ltd.

6

Slide © NASA, 2004. See http://robotics.nasa.gov/

7

Slide © NASA, 2004. See http://robotics.nasa.gov/

8

Slide © NASA, 2004. See http://robotics.nasa.gov/

9

NASA Spirit Rover (MER)

Image © Neil English, Exploring Mars, Pole Star Publications Ltd.

Stereo
imaging and
navigation
cameras

Direct
-
to
-
Earth uplink

Poseable
instrument
package

Multi
-
wheel
drive

Special
hazard
cameras

Strut for
long reach

10

Slide © NASA, 2004. See http://robotics.nasa.gov/

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Slide © NASA, 2004. See http://robotics.nasa.gov/

12

Deep Space Communications


Distance to Mars


Closest to Earth: 54.5 million km


Furthest from Earth: 401.3 million km


Signal times


Based on c = 299,793 km/s


~ 3.03 minutes (Earth/Mars closest)


~ 22.31 minutes (Earth/Mars farthest)


Consequences


Base cannot react in real
-
time


Rover must act autonomously

13

Mission Management


Base station (Earth)


Mission goals, priorities, master control


Master data uplink, processing science results


Local station (Orbiter, Lander)


Local area planning, local priorities, alternate tasks


Global hazards, sandstorm warnings, rover safety


local data uplink, local processing, data reduction


Rover


Navigation, terrain following, obstacle avoidance


Experiment selection, control, completion

14

Hardware Issues


Satellite uplink


Need for Earth/Mars, Rover/Orbiter communications


What hardware, comms. protocols, power rating?


Microcontrollers


Small processors to read sensors and drive devices


What memory, buses/ports, power rating, software?


Communications bus


How many sensors, devices, moving parts to control?


Devices and sensors


What devices/sensors? What registers to read/write?

15

Navigation


Global Positioning System (GPS)


Could the Rover use this to find out its location?


How many Orbiters/registration signals?


How often/accurately measured? How important?


Tilt Sensors (Accelerometers)


Compute velocity, position from known starting point using
internal acceleration sensors


Integrate acceleration over time for velocity, velocity over
time for distance


but how to correct drift errors?


Ultrasonic sensors


Echo location system for computing distance from target


Use in Martian atmosphere for obstacle avoidance?

16

Ultrasonic Sensors


SRF08 ultrasonic sensor


On
-
chip microcontroller PIC
determines distance from
objects


Detects objects from 3cm


6m


I2C bus communicates with
external TINI


TINI concentrates on high
-
level control

Product image © Total Robots. SRF08 sensors available from Total Robots

17

Instrument Packages


Navigation


Stereo navcams, hazcams, laser striper, ultrasound, inertial
compass (no magnetic field)


Science


360


panoramic camera, HD cameras


Spectrometers: infrared/thermal emission (carbon,
minerals), Moessbauer (iron
-
bearing properties)


Rock abrasion tool


Microscope (spores, bacteria)


Wet science chemistry (lifesign reactions)

18

Software Issues


Multi
-
tier


AI for high
-
level autonomous decisions


Stereo vision algorithms for navigation


Sensing, analysis and data compression


Reliability


Triple
-
redundant voting system?


Cosmic ray damage: reboot and/or reconfigure?


Failsafe shutdown options


Communications


Coordinate rover, lander, orbiter?

19

Slide © NASA, 2004. See http://robotics.nasa.gov/

20

Slide © NASA, 2004. See http://robotics.nasa.gov/

21

Slide © NASA, 2004. See http://robotics.nasa.gov/

22

Slide © NASA, 2004. See http://robotics.nasa.gov/

23

Slide © NASA, 2004. See http://robotics.nasa.gov/

24

Slide © NASA, 2004. See http://robotics.nasa.gov/

25

Slide © NASA, 2004. See http://robotics.nasa.gov/

26

Slide © NASA, 2004. See http://robotics.nasa.gov/

27

Slide © NASA, 2004. See http://robotics.nasa.gov/

28

Slide © NASA, 2004. See http://robotics.nasa.gov/

29

Future Missions


NASA Phoenix Scout


Launched in 2007, Polar Lander


Wet chemistry, water
-
finding, life?


NASA Mars Science Laboratory


Launch in 2009, 10*payload of MER


Skycrane rocket lander, nuclear power


Projected Biomorph Swarms


Aerobot/rotorcraft, biomorph/micro
-
rovers and subsurface
penetrators


Work as cooperating swarm, resilient to failures


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NASA’s Phoenix Scout

Lander only
mission

Mission to
northern
polar region

Subsurface
water ice?

Wet water
chemistry
experiments

Image © Neil English, Exploring Mars, Pole Star Publications Ltd.

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NASA Mars Science Laboratory

Direct
-
to
-
Earth uplink

Much larger
rover (*10)

Image © Neil English, Exploring Mars, Pole Star Publications Ltd.

Nuclear
powered

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Stanford: Mesicopter Swarm

Swarm
rotorcraft

Robust and
redundant

Cooperating
agents

Image © NASA/DoD Second Biomorphic Explorers Workshop, JPL 2000.

Work by Ilan Kroo, Peter Kunz, Dept. of Aeronautics and Astronomy, Stanford University

33

Swarm Exploration

Image © NASA/DoD Second Biomorphic Explorers Workshop, JPL 2000.

Work by Ilan Kroo, Peter Kunz, Dept. of Aeronautics and Astronomy, Stanford University

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ANTS Mission

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Swarm Control


Massively parallel system


How to predict all possible interactions?


Cannot hope to test all behaviours


System must be correct by design


Tools for understanding, specifying swarms


Individual
-
based modelling (FLAME tool)


models cellular automata


Formal method: X
-
Machines


specifies cellular automata


Any

Questions?